Transplanting apparatus is well known in the art. Typical transplanters, which transplant from a plant tray, are shown in U.S. Pat. Nos. 4,644,880; 5,431,116; 5,573,558; 5,676,072; 6,073,564; and 6,634,306. Frequently there are skips between seedlings which may occur when seeds in a tray row fail to grow into seedlings. Transplanters which try to eliminate skips include U.S. Pat. No. 6,327,986 which discloses three separate sets of sensors to look for plant skips and advance a root ball chamber belt assembly one cell to make up for skips and eject the deficient root ball at the same time. U.S. Pat. No. 6,080,951 discloses another approach to overcome the seedling tray skip problem. These approaches rely heavily on the accuracy of detectors to sense the presence of plant foliage. Considering the chaotic nature of the foliage and the necessary speed to be efficient, there is substantial room for error in these systems. Prior U.S. published application No. US-2009-0031935-A1 uses conveyor belts which push together the root balls of the rows of plants extracted from a plant tray.
Unfortunately, the root balls in a tray, when received at the transplanter, are not always firm and fully packed, making the subsequent handling somewhat difficult. Thus the root ball may tip over when placed on a conveyor belt. In addition, it may be difficult for a pinch disk to grab the root ball.
In U.S. published application No. US-2009-0031935-A1, the subject matter of which is incorporated herein by reference thereto, after gaps between seedlings have been eliminated, individual seedlings pass through a drop tube to a mechanism for discharging the seedlings one at a time to the ground with a desired spacing between the seedlings.
It is a feature of the foregoing patent application that the transplanter has a forward pair of transfer disks; a rear pair of planter disks; and an air knife mounted adjacent the forward pair of transfer disks for extending the stem and foliage of a seedling while in the forward pair of transfer disks for proper engagement by the rear pair of planting disks. It has been found that approximately 95% of seedlings will pass through a drop-tube type planter system without issues. The last 5% consists of plants with poor root systems, crooked stems, dwarfed size and soft stems. These types of plants tend to drag on the side of the drop tube and travel slowly because the soil has dislodged from the root ball or tipped over because of the soft stems. This results in skips and drop tube plugging issues.